African-Americans share a disproportionate burden of lung cancer incidence and mortality; Mexican-Americans exhibit substantially lower rates. These racial differences may represent interactions of environmental and genetic influences. This study merges and extends two already funded ecogenetic studies of lung cancer in order to integrate molecular and cytogenetic markers of lung cancer susceptibility into a case-control study of 100 black African-American and 100 Mexican-American patients with previously untreated lung cancer. Cases will be ascertained from the University of Texas M.D. Anderson Cancer Center, St. Joseph Hospital, Hermann Hospital and Lyndon Baines Johnson Hospital. Two-hundred (200) controls from each ethnic group, selected from local community centers will be age- and sex- frequency matched to the cases. The molecular component will focus on estimating the prevalence of genetic polymorphisms in two cytochrome P-450 genes (CYP 2D6, CYP lAl) and alleles of glutathione-S-transferase type mu. These genetic traits have been previously associated with lung cancer in predominately white populations. The cytogenetic component will focus on two markers of chromosomal sensitivity in peripheral blood lymphocytes: bleomycin-induced chromatid breaks and diepoxybutane-induced sister chromatid exchanges (SCEs). Since lung cancer is the leading cause of cancer mortality, the identification of genetic markers of risk has great potential for cancer control. The use of multiple genetic markers of risk within the same population provides a highly efficient means to simultaneously test several hypotheses concerning genetic contributions to' cancer risk in minority populations. In addition by making use of established multi-center resources, the opportunity exists to carry out inter-laboratory comparisons of marker performance.